/* deflate.c -- compress data using the deflation algorithm
 * Copyright (C) 1995-1998 Jean-loup Gailly.
 * For conditions of distribution and use, see copyright notice in zlib.h 
 */

/*
 *  ALGORITHM
 *
 *      The "deflation" process depends on being able to identify portions
 *      of the input text which are identical to earlier input (within a
 *      sliding window trailing behind the input currently being processed).
 *
 *      The most straightforward technique turns out to be the fastest for
 *      most input files: try all possible matches and select the longest.
 *      The key feature of this algorithm is that insertions into the string
 *      dictionary are very simple and thus fast, and deletions are avoided
 *      completely. Insertions are performed at each input character, whereas
 *      string matches are performed only when the previous match ends. So it
 *      is preferable to spend more time in matches to allow very fast string
 *      insertions and avoid deletions. The matching algorithm for small
 *      strings is inspired from that of Rabin & Karp. A brute force approach
 *      is used to find longer strings when a small match has been found.
 *      A similar algorithm is used in comic (by Jan-Mark Wams) and freeze
 *      (by Leonid Broukhis).
 *         A previous version of this file used a more sophisticated algorithm
 *      (by Fiala and Greene) which is guaranteed to run in linear amortized
 *      time, but has a larger average cost, uses more memory and is patented.
 *      However the F&G algorithm may be faster for some highly redundant
 *      files if the parameter max_chain_length (described below) is too large.
 *
 *  ACKNOWLEDGEMENTS
 *
 *      The idea of lazy evaluation of matches is due to Jan-Mark Wams, and
 *      I found it in 'freeze' written by Leonid Broukhis.
 *      Thanks to many people for bug reports and testing.
 *
 *  REFERENCES
 *
 *      Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".
 *      Available in ftp://ds.internic.net/rfc/rfc1951.txt
 *
 *      A description of the Rabin and Karp algorithm is given in the book
 *         "Algorithms" by R. Sedgewick, Addison-Wesley, p252.
 *
 *      Fiala,E.R., and Greene,D.H.
 *         Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595
 *
 */

/* @(#) $Id$ */

#include "deflate.h"

   const char deflate_copyright[] =
   " deflate 1.1.3 Copyright 1995-1998 Jean-loup Gailly ";
/*
  If you use the zlib library in a product, an acknowledgment is welcome
  in the documentation of your product. If for some reason you cannot
  include such an acknowledgment, I would appreciate that you keep this
  copyright string in the executable of your product.
 */

/* ===========================================================================
 *  Function prototypes.
 */
   typedef enum {
    need_more,      /* block not completed, need more input or more output */
    block_done,     /* block flush performed */
    finish_started, /* finish started, need only more output at next deflate */
    finish_done     /* finish done, accept no more input or output */
   } block_state;

   typedef block_state (*compress_func) OF((deflate_state *s, int flush));
/* Compression function. Returns the block state after the call. */

   local void fill_window    OF((deflate_state *s));
   local block_state deflate_stored OF((deflate_state *s, int flush));
   local block_state deflate_fast   OF((deflate_state *s, int flush));
   local block_state deflate_slow   OF((deflate_state *s, int flush));
   local void lm_init        OF((deflate_state *s));
   local void putShortMSB    OF((deflate_state *s, uInt b));
   local void flush_pending  OF((z_streamp strm));
   local int read_buf        OF((z_streamp strm, Bytef *buf, unsigned size));
#ifdef ASMV
      void match_init OF((void)); /* asm code initialization */
      uInt longest_match  OF((deflate_state *s, IPos cur_match));
#else
   local uInt longest_match  OF((deflate_state *s, IPos cur_match));
#endif

#ifdef DEBUG
local  void check_match OF((deflate_state *s, IPos start, IPos match,
                            int length));
#endif

/* ===========================================================================
 * Local data
 */

#define NIL 0
/* Tail of hash chains */

#ifndef TOO_FAR
#  define TOO_FAR 4096
#endif
/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */

#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
/* Minimum amount of lookahead, except at the end of the input file.
 * See deflate.c for comments about the MIN_MATCH+1.
 */

/* Values for max_lazy_match, good_match and max_chain_length, depending on
 * the desired pack level (0..9). The values given below have been tuned to
 * exclude worst case performance for pathological files. Better values may be
 * found for specific files.
 */
   typedef struct config_s {
      ush good_length; /* reduce lazy search above this match length */
      ush max_lazy;    /* do not perform lazy search above this match length */
      ush nice_length; /* quit search above this match length */
      ush max_chain;
      compress_func func;
   } config;

   local const config configuration_table[10] = {
   /*      good lazy nice chain */
   /* 0 */ {0,    0,  0,    0, deflate_stored},  /* store only */
   /* 1 */ {4,    4,  8,    4, deflate_fast}, /* maximum speed, no lazy matches */
   /* 2 */ {4,    5, 16,    8, deflate_fast},
   /* 3 */ {4,    6, 32,   32, deflate_fast},
   
   /* 4 */ {4,    4, 16,   16, deflate_slow},  /* lazy matches */
   /* 5 */ {8,   16, 32,   32, deflate_slow},
   /* 6 */ {8,   16, 128, 128, deflate_slow},
   /* 7 */ {8,   32, 128, 256, deflate_slow},
   /* 8 */ {32, 128, 258, 1024, deflate_slow},
   /* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* maximum compression */

/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
 * meaning.
 */

#define EQUAL 0
/* result of memcmp for equal strings */

   struct static_tree_desc_s {int dummy;}; /* for buggy compilers */

/* ===========================================================================
 * Update a hash value with the given input byte
 * IN  assertion: all calls to to UPDATE_HASH are made with consecutive
 *    input characters, so that a running hash key can be computed from the
 *    previous key instead of complete recalculation each time.
 */
#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)


/* ===========================================================================
 * Insert string str in the dictionary and set match_head to the previous head
 * of the hash chain (the most recent string with same hash key). Return
 * the previous length of the hash chain.
 * If this file is compiled with -DFASTEST, the compression level is forced
 * to 1, and no hash chains are maintained.
 * IN  assertion: all calls to to INSERT_STRING are made with consecutive
 *    input characters and the first MIN_MATCH bytes of str are valid
 *    (except for the last MIN_MATCH-1 bytes of the input file).
 */
#ifdef FASTEST
#define INSERT_STRING(s, str, match_head) \
   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
    match_head = s->head[s->ins_h], \
    s->head[s->ins_h] = (Pos)(str))
#else
#define INSERT_STRING(s, str, match_head) \
   (UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \
    s->prev[(str) & s->w_mask] = match_head = s->head[s->ins_h], \
    s->head[s->ins_h] = (Pos)(str))
#endif

/* ===========================================================================
 * Initialize the hash table (avoiding 64K overflow for 16 bit systems).
 * prev[] will be initialized on the fly.
 */
#define CLEAR_HASH(s) \
    s->head[s->hash_size-1] = NIL; \
    zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));

/* ========================================================================= */
    int ZEXPORT deflateInit_(z_streamp strm, int level, const char *version, int stream_size){
      return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,
          Z_DEFAULT_STRATEGY, version, stream_size);
    /* To do: ignore strm->next_in if we use it as window */
   }

/* ========================================================================= */
    int ZEXPORT deflateInit2_(
    z_streamp strm,
    int  level,
    int  method,
    int  windowBits,
    int  memLevel,
    int  strategy,
    const char *version,
    int stream_size)
   {
      deflate_state *s;
      int noheader = 0;
      static const char* my_version = ZLIB_VERSION;
   
      ushf *overlay;
    /* We overlay pending_buf and d_buf+l_buf. This works since the average
     * output size for (length,distance) codes is <= 24 bits.
     */
   
      if (version == Z_NULL || version[0] != my_version[0] ||
        stream_size != sizeof(z_stream)) {
         return Z_VERSION_ERROR;
      }
      if (strm == Z_NULL) 
         return Z_STREAM_ERROR;
   
      strm->msg = Z_NULL;
      if (strm->zalloc == Z_NULL) {
         strm->zalloc = zcalloc;
         strm->opaque = (voidpf)0;
      }
      if (strm->zfree == Z_NULL) strm->zfree = zcfree;
   
      if (level == Z_DEFAULT_COMPRESSION) level = 6;
   #ifdef FASTEST
    level = 1;
   #endif
   
      if (windowBits < 0) { /* undocumented feature: suppress zlib header */
         noheader = 1;
         windowBits = -windowBits;
      }
      if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||
        windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||
      strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
         return Z_STREAM_ERROR;
      }
      s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));
      if (s == Z_NULL) 
         return Z_MEM_ERROR;
      strm->state = (struct internal_state FAR *)s;
      s->strm = strm;
   
      s->noheader = noheader;
      s->w_bits = windowBits;
      s->w_size = 1 << s->w_bits;
      s->w_mask = s->w_size - 1;
   
      s->hash_bits = memLevel + 7;
      s->hash_size = 1 << s->hash_bits;
      s->hash_mask = s->hash_size - 1;
      s->hash_shift =  ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);
   
      s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));
      s->prev   = (Posf *)  ZALLOC(strm, s->w_size, sizeof(Pos));
      s->head   = (Posf *)  ZALLOC(strm, s->hash_size, sizeof(Pos));
   
      s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */
   
      overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);
      s->pending_buf = (uchf *) overlay;
      s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);
   
      if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||
        s->pending_buf == Z_NULL) {
         strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);
         deflateEnd (strm);
         return Z_MEM_ERROR;
      }
      s->d_buf = overlay + s->lit_bufsize/sizeof(ush);
      s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;
   
      s->level = level;
      s->strategy = strategy;
      s->method = (Byte)method;
   
      return deflateReset(strm);
   }

/* ========================================================================= */
    int ZEXPORT deflateSetDictionary (
    z_streamp strm,
    const Bytef *dictionary,
    uInt  dictLength)
   {
      deflate_state *s;
      uInt length = dictLength;
      uInt n;
      IPos hash_head = 0;
   
      if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||
        strm->state->status != INIT_STATE) 
         return Z_STREAM_ERROR;
   
      s = strm->state;
      strm->adler = adler32(strm->adler, dictionary, dictLength);
   
      if (length < MIN_MATCH) 
         return Z_OK;
      if (length > MAX_DIST(s)) {
         length = MAX_DIST(s);
      #ifndef USE_DICT_HEAD
         dictionary += dictLength - length; /* use the tail of the dictionary */
      #endif
      }
      zmemcpy(s->window, dictionary, length);
      s->strstart = length;
      s->block_start = (long)length;
   
    /* Insert all strings in the hash table (except for the last two bytes).
     * s->lookahead stays null, so s->ins_h will be recomputed at the next
     * call of fill_window.
     */
      s->ins_h = s->window[0];
      UPDATE_HASH(s, s->ins_h, s->window[1]);
      for (n = 0; n <= length - MIN_MATCH; n++) {
         INSERT_STRING(s, n, hash_head);
      }
      if (hash_head) hash_head = 0;  /* to make compiler happy */
      return Z_OK;
   }

/* ========================================================================= */
    int ZEXPORT deflateReset (z_streamp strm)
   {
      deflate_state *s;
    
      if (strm == Z_NULL || strm->state == Z_NULL ||
        strm->zalloc == Z_NULL || strm->zfree == Z_NULL) 
         return Z_STREAM_ERROR;
   
      strm->total_in = strm->total_out = 0;
      strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */
      strm->data_type = Z_UNKNOWN;
   
      s = (deflate_state *)strm->state;
      s->pending = 0;
      s->pending_out = s->pending_buf;
   
      if (s->noheader < 0) {
         s->noheader = 0; /* was set to -1 by deflate(..., Z_FINISH); */
      }
      s->status = s->noheader ? BUSY_STATE : INIT_STATE;
      strm->adler = 1;
      s->last_flush = Z_NO_FLUSH;
   
      _tr_init(s);
      lm_init(s);
   
      return Z_OK;
   }

/* ========================================================================= */
    int ZEXPORT deflateParams(
    z_streamp strm,
    int level,
    int strategy)
   {
      deflate_state *s;
      compress_func func;
      int err = Z_OK;
   
      if (strm == Z_NULL || strm->state == Z_NULL) 
         return Z_STREAM_ERROR;
      s = strm->state;
   
      if (level == Z_DEFAULT_COMPRESSION) {
         level = 6;
      }
      if (level < 0 || level > 9 || strategy < 0 || strategy > Z_HUFFMAN_ONLY) {
         return Z_STREAM_ERROR;
      }
      func = configuration_table[s->level].func;
   
      if (func != configuration_table[level].func && strm->total_in != 0) {
      /* Flush the last buffer: */
         err = deflate(strm, Z_PARTIAL_FLUSH);
      }
      if (s->level != level) {
         s->level = level;
         s->max_lazy_match   = configuration_table[level].max_lazy;
         s->good_match       = configuration_table[level].good_length;
         s->nice_match       = configuration_table[level].nice_length;
         s->max_chain_length = configuration_table[level].max_chain;
      }
      s->strategy = strategy;
      return err;
   }

/* =========================================================================
 * Put a short in the pending buffer. The 16-bit value is put in MSB order.
 * IN assertion: the stream state is correct and there is enough room in
 * pending_buf.
 */
    local void putShortMSB (deflate_state *s, uInt b){
      put_byte(s, (Byte)(b >> 8));
      put_byte(s, (Byte)(b & 0xff));
   }   

/* =========================================================================
 * Flush as much pending output as possible. All deflate() output goes
 * through this function so some applications may wish to modify it
 * to avoid allocating a large strm->next_out buffer and copying into it.
 * (See also read_buf()).
 */
    local void flush_pending(z_streamp strm){
      unsigned len = strm->state->pending;
   
      if (len > strm->avail_out) len = strm->avail_out;
      if (len == 0) 
         return;
   
      zmemcpy(strm->next_out, strm->state->pending_out, len);
      strm->next_out  += len;
      strm->state->pending_out  += len;
      strm->total_out += len;
      strm->avail_out  -= len;
      strm->state->pending -= len;
      if (strm->state->pending == 0) {
         strm->state->pending_out = strm->state->pending_buf;
      }
   }

/* ========================================================================= */
    int ZEXPORT deflate (z_streamp strm, int flush)
   {
      int old_flush; /* value of flush param for previous deflate call */
      deflate_state *s;
   
      if (strm == Z_NULL || strm->state == Z_NULL ||
      flush > Z_FINISH || flush < 0) {
         return Z_STREAM_ERROR;
      }
      s = strm->state;
   
      if (strm->next_out == Z_NULL ||
        (strm->next_in == Z_NULL && strm->avail_in != 0) ||
      (s->status == FINISH_STATE && flush != Z_FINISH)) {
         ERR_RETURN(strm, Z_STREAM_ERROR);
      }
      if (strm->avail_out == 0) 
         ERR_RETURN(strm, Z_BUF_ERROR);
   
      s->strm = strm; /* just in case */
      old_flush = s->last_flush;
      s->last_flush = flush;
   
    /* Write the zlib header */
      if (s->status == INIT_STATE) {
      
         uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;
         uInt level_flags = (s->level-1) >> 1;
      
         if (level_flags > 3) level_flags = 3;
         header |= (level_flags << 6);
         if (s->strstart != 0) header |= PRESET_DICT;
         header += 31 - (header % 31);
      
         s->status = BUSY_STATE;
         putShortMSB(s, header);
      
      /* Save the adler32 of the preset dictionary: */
         if (s->strstart != 0) {
            putShortMSB(s, (uInt)(strm->adler >> 16));
            putShortMSB(s, (uInt)(strm->adler & 0xffff));
         }
         strm->adler = 1L;
      }
   
    /* Flush as much pending output as possible */
      if (s->pending != 0) {
         flush_pending(strm);
         if (strm->avail_out == 0) {
         /* Since avail_out is 0, deflate will be called again with
         * more output space, but possibly with both pending and
         * avail_in equal to zero. There won't be anything to do,
         * but this is not an error situation so make sure we
         * return OK instead of BUF_ERROR at next call of deflate:
             */
            s->last_flush = -1;
            return Z_OK;
         }
      
      /* Make sure there is something to do and avoid duplicate consecutive
      * flushes. For repeated and useless calls with Z_FINISH, we keep
      * returning Z_STREAM_END instead of Z_BUFF_ERROR.
      */
      } 
      else if (strm->avail_in == 0 && flush <= old_flush &&
          flush != Z_FINISH) {
         ERR_RETURN(strm, Z_BUF_ERROR);
      }
   
    /* User must not provide more input after the first FINISH: */
      if (s->status == FINISH_STATE && strm->avail_in != 0) {
         ERR_RETURN(strm, Z_BUF_ERROR);
      }
   
    /* Start a new block or continue the current one.
     */
      if (strm->avail_in != 0 || s->lookahead != 0 ||
        (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {
         block_state bstate;
      
         bstate = (*(configuration_table[s->level].func))(s, flush);
      
         if (bstate == finish_started || bstate == finish_done) {
            s->status = FINISH_STATE;
         }
         if (bstate == need_more || bstate == finish_started) {
            if (strm->avail_out == 0) {
               s->last_flush = -1; /* avoid BUF_ERROR next call, see above */
            }
            return Z_OK;
         /* If flush != Z_NO_FLUSH && avail_out == 0, the next call
         * of deflate should use the same flush parameter to make sure
         * that the flush is complete. So we don't have to output an
         * empty block here, this will be done at next call. This also
         * ensures that for a very small output buffer, we emit at most
         * one empty block.
         */
         }
         if (bstate == block_done) {
            if (flush == Z_PARTIAL_FLUSH) {
               _tr_align(s);
            } 
            else { /* FULL_FLUSH or SYNC_FLUSH */
               _tr_stored_block(s, (char*)0, 0L, 0);
                /* For a full flush, this empty block will be recognized
                 * as a special marker by inflate_sync().
                 */
               if (flush == Z_FULL_FLUSH) {
                    CLEAR_HASH(s);             /* forget history */
               }
            }
            flush_pending(strm);
            if (strm->avail_out == 0) {
               s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */
               return Z_OK;
            }
         }
      }
    Assert(strm->avail_out > 0, "bug2");
   
      if (flush != Z_FINISH) 
         return Z_OK;
      if (s->noheader) 
         return Z_STREAM_END;
   
    /* Write the zlib trailer (adler32) */
      putShortMSB(s, (uInt)(strm->adler >> 16));
      putShortMSB(s, (uInt)(strm->adler & 0xffff));
      flush_pending(strm);
    /* If avail_out is zero, the application will call deflate again
     * to flush the rest.
     */
      s->noheader = -1; /* write the trailer only once! */
      return s->pending != 0 ? Z_OK : Z_STREAM_END;
   }

/* ========================================================================= */
    int ZEXPORT deflateEnd (z_streamp strm){
      int status;
   
      if (strm == Z_NULL || strm->state == Z_NULL) 
         return Z_STREAM_ERROR;
   
      status = strm->state->status;
      if (status != INIT_STATE && status != BUSY_STATE &&
      status != FINISH_STATE) {
         return Z_STREAM_ERROR;
      }
   
    /* Deallocate in reverse order of allocations: */
      TRY_FREE(strm, strm->state->pending_buf);
      TRY_FREE(strm, strm->state->head);
      TRY_FREE(strm, strm->state->prev);
      TRY_FREE(strm, strm->state->window);
   
      ZFREE(strm, strm->state);
      strm->state = Z_NULL;
   
      return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;
   }

/* =========================================================================
 * Copy the source state to the destination state.
 * To simplify the source, this is not supported for 16-bit MSDOS (which
 * doesn't have enough memory anyway to duplicate compression states).
 */
    int ZEXPORT deflateCopy (z_streamp dest, z_streamp source){
   #ifdef MAXSEG_64K
    return Z_STREAM_ERROR;
   #else
      deflate_state *ds;
      deflate_state *ss;
      ushf *overlay;
   
   
      if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {
         return Z_STREAM_ERROR;
      }
   
      ss = source->state;
   
      *dest = *source;
   
      ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));
      if (ds == Z_NULL) 
         return Z_MEM_ERROR;
      dest->state = (struct internal_state FAR *) ds;
      *ds = *ss;
      ds->strm = dest;
   
      ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));
      ds->prev   = (Posf *)  ZALLOC(dest, ds->w_size, sizeof(Pos));
      ds->head   = (Posf *)  ZALLOC(dest, ds->hash_size, sizeof(Pos));
      overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);
      ds->pending_buf = (uchf *) overlay;
   
      if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||
        ds->pending_buf == Z_NULL) {
         deflateEnd (dest);
         return Z_MEM_ERROR;
      }
    /* following zmemcpy do not work for 16-bit MSDOS */
      zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));
      zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));
      zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));
      zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);
   
      ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);
      ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);
      ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;
   
      ds->l_desc.dyn_tree = ds->dyn_ltree;
      ds->d_desc.dyn_tree = ds->dyn_dtree;
      ds->bl_desc.dyn_tree = ds->bl_tree;
   
      return Z_OK;
   #endif
   }

/* ===========================================================================
 * Read a new buffer from the current input stream, update the adler32
 * and total number of bytes read.  All deflate() input goes through
 * this function so some applications may wish to modify it to avoid
 * allocating a large strm->next_in buffer and copying from it.
 * (See also flush_pending()).
 */
    local int read_buf(z_streamp strm, Bytef *buf, unsigned size){
      unsigned len = strm->avail_in;
   
      if (len > size) len = size;
      if (len == 0) 
         return 0;
   
      strm->avail_in  -= len;
   
      if (!strm->state->noheader) {
         strm->adler = adler32(strm->adler, strm->next_in, len);
      }
      zmemcpy(buf, strm->next_in, len);
      strm->next_in  += len;
      strm->total_in += len;
   
      return (int)len;
   }

/* ===========================================================================
 * Initialize the "longest match" routines for a new zlib stream
 */
    local void lm_init (deflate_state *s){
      s->window_size = (ulg)2L*s->w_size;
   
    CLEAR_HASH(s);
   
    /* Set the default configuration parameters:
     */
      s->max_lazy_match   = configuration_table[s->level].max_lazy;
      s->good_match       = configuration_table[s->level].good_length;
      s->nice_match       = configuration_table[s->level].nice_length;
      s->max_chain_length = configuration_table[s->level].max_chain;
   
      s->strstart = 0;
      s->block_start = 0L;
      s->lookahead = 0;
      s->match_length = s->prev_length = MIN_MATCH-1;
      s->match_available = 0;
      s->ins_h = 0;
   #ifdef ASMV
    match_init(); /* initialize the asm code */
   #endif
   }

/* ===========================================================================
 * Set match_start to the longest match starting at the given string and
 * return its length. Matches shorter or equal to prev_length are discarded,
 * in which case the result is equal to prev_length and match_start is
 * garbage.
 * IN assertions: cur_match is the head of the hash chain for the current
 *   string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
 * OUT assertion: the match length is not greater than s->lookahead.
 */
#ifndef ASMV
/* For 80x86 and 680x0, an optimized version will be provided in match.asm or
 * match.S. The code will be functionally equivalent.
 */
#ifndef FASTEST
    local uInt longest_match(deflate_state *s,IPos cur_match){
      unsigned chain_length = s->max_chain_length;/* max hash chain length */
      register Bytef *scan = s->window + s->strstart; /* current string */
      register Bytef *match;                       /* matched string */
      register int len;                           /* length of current match */
      int best_len = s->prev_length;              /* best match length so far */
      int nice_match = s->nice_match;             /* stop if match long enough */
      IPos limit = s->strstart > (IPos)MAX_DIST(s) ?
        s->strstart - (IPos)MAX_DIST(s) : NIL;
    /* Stop when cur_match becomes <= limit. To simplify the code,
     * we prevent matches with the string of window index 0.
     */
      Posf *prev = s->prev;
      uInt wmask = s->w_mask;
   
   #ifdef UNALIGNED_OK
    /* Compare two bytes at a time. Note: this is not always beneficial.
     * Try with and without -DUNALIGNED_OK to check.
     */
    register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;
    register ush scan_start = *(ushf*)scan;
    register ush scan_end   = *(ushf*)(scan+best_len-1);
   #else
      register Bytef *strend = s->window + s->strstart + MAX_MATCH;
      register Byte scan_end1  = scan[best_len-1];
      register Byte scan_end   = scan[best_len];
   #endif
   
    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
     * It is easy to get rid of this optimization if necessary.
     */
    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");
   
    /* Do not waste too much time if we already have a good match: */
      if (s->prev_length >= s->good_match) {
         chain_length >>= 2;
      }
    /* Do not look for matches beyond the end of the input. This is necessary
     * to make deflate deterministic.
     */
      if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;
   
    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");
   
      do {
        Assert(cur_match < s->strstart, "no future");
         match = s->window + cur_match;
      
        /* Skip to next match if the match length cannot increase
         * or if the match length is less than 2:
         */
      #if (defined(UNALIGNED_OK) && MAX_MATCH == 258)
        /* This code assumes sizeof(unsigned short) == 2. Do not use
         * UNALIGNED_OK if your compiler uses a different size.
         */
        if (*(ushf*)(match+best_len-1) != scan_end ||
            *(ushf*)match != scan_start) continue;
      
        /* It is not necessary to compare scan[2] and match[2] since they are
         * always equal when the other bytes match, given that the hash keys
         * are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at
         * strstart+3, +5, ... up to strstart+257. We check for insufficient
         * lookahead only every 4th comparison; the 128th check will be made
         * at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is
         * necessary to put more guard bytes at the end of the window, or
         * to check more often for insufficient lookahead.
         */
        Assert(scan[2] == match[2], "scan[2]?");
        scan++, match++;
        do {
        } while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
                 *(ushf*)(scan+=2) == *(ushf*)(match+=2) &&
                 scan < strend);
        /* The funny "do {}" generates better code on most compilers */
      
        /* Here, scan <= window+strstart+257 */
        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
        if (*scan == *match) scan++;
      
        len = (MAX_MATCH - 1) - (int)(strend-scan);
        scan = strend - (MAX_MATCH-1);
      
      #else /* UNALIGNED_OK */
      
         if (match[best_len]   != scan_end  ||
            match[best_len-1] != scan_end1 ||
            *match            != *scan     ||
            *++match          != scan[1])      
            continue;
      
        /* The check at best_len-1 can be removed because it will be made
         * again later. (This heuristic is not always a win.)
         * It is not necessary to compare scan[2] and match[2] since they
         * are always equal when the other bytes match, given that
         * the hash keys are equal and that HASH_BITS >= 8.
         */
         scan += 2, match++;
        Assert(*scan == *match, "match[2]?");
      
        /* We check for insufficient lookahead only every 8th comparison;
         * the 256th check will be made at strstart+258.
         */
         do {
         } while (*++scan == *++match && *++scan == *++match &&
                 *++scan == *++match && *++scan == *++match &&
                 *++scan == *++match && *++scan == *++match &&
                 *++scan == *++match && *++scan == *++match &&
                 scan < strend);
      
        Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");
      
         len = MAX_MATCH - (int)(strend - scan);
         scan = strend - MAX_MATCH;
      
      #endif /* UNALIGNED_OK */
      
         if (len > best_len) {
            s->match_start = cur_match;
            best_len = len;
            if (len >= nice_match) 
               break;
         #ifdef UNALIGNED_OK
            scan_end = *(ushf*)(scan+best_len-1);
         #else
            scan_end1  = scan[best_len-1];
            scan_end   = scan[best_len];
         #endif
         }
      } while ((cur_match = prev[cur_match & wmask]) > limit
             && --chain_length != 0);
   
      if ((uInt)best_len <= s->lookahead) 
         return (uInt)best_len;
      return s->lookahead;
   }

#else /* FASTEST */
/* ---------------------------------------------------------------------------
 * Optimized version for level == 1 only
 */
local uInt longest_match(s, cur_match)
    deflate_state *s;
    IPos cur_match;                             /* current match */
{
    register Bytef *scan = s->window + s->strstart; /* current string */
    register Bytef *match;                       /* matched string */
    register int len;                           /* length of current match */
    register Bytef *strend = s->window + s->strstart + MAX_MATCH;

    /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
     * It is easy to get rid of this optimization if necessary.
     */
    Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");

    Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");

    Assert(cur_match < s->strstart, "no future");

    match = s->window + cur_match;

    /* Return failure if the match length is less than 2:
     */
    if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;

    /* The check at best_len-1 can be removed because it will be made
     * again later. (This heuristic is not always a win.)
     * It is not necessary to compare scan[2] and match[2] since they
     * are always equal when the other bytes match, given that
     * the hash keys are equal and that HASH_BITS >= 8.
     */
    scan += 2, match += 2;
    Assert(*scan == *match, "match[2]?");

    /* We check for insufficient lookahead only every 8th comparison;
     * the 256th check will be made at strstart+258.
     */
    do {
    } while (*++scan == *++match && *++scan == *++match &&
	     *++scan == *++match && *++scan == *++match &&
	     *++scan == *++match && *++scan == *++match &&
	     *++scan == *++match && *++scan == *++match &&
	     scan < strend);

    Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");

    len = MAX_MATCH - (int)(strend - scan);

    if (len < MIN_MATCH) return MIN_MATCH - 1;

    s->match_start = cur_match;
    return len <= s->lookahead ? len : s->lookahead;
}
#endif /* FASTEST */
#endif /* ASMV */

#ifdef DEBUG
/* ===========================================================================
 * Check that the match at match_start is indeed a match.
 */
local void check_match(s, start, match, length)
    deflate_state *s;
    IPos start, match;
    int length;
{
    /* check that the match is indeed a match */
    if (zmemcmp(s->window + match,
                s->window + start, length) != EQUAL) {
        fprintf(stderr, " start %u, match %u, length %d\n",
		start, match, length);
        do {
	    fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);
	} while (--length != 0);
        z_error("invalid match");
    }
    if (z_verbose > 1) {
        fprintf(stderr,"\\[%d,%d]", start-match, length);
        do { putc(s->window[start++], stderr); } while (--length != 0);
    }
}
#else
#  define check_match(s, start, match, length)
#endif

/* ===========================================================================
 * Fill the window when the lookahead becomes insufficient.
 * Updates strstart and lookahead.
 *
 * IN assertion: lookahead < MIN_LOOKAHEAD
 * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD
 *    At least one byte has been read, or avail_in == 0; reads are
 *    performed for at least two bytes (required for the zip translate_eol
 *    option -- not supported here).
 */
    local void fill_window(deflate_state *s){
      register unsigned n, m;
      register Posf *p;
      unsigned more;    /* Amount of free space at the end of the window. */
      uInt wsize = s->w_size;
   
      do {
         more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);
      
        /* Deal with !@#$% 64K limit: */
         if (more == 0 && s->strstart == 0 && s->lookahead == 0) {
            more = wsize;
         
         } 
         else if (more == (unsigned)(-1)) {
            /* Very unlikely, but possible on 16 bit machine if strstart == 0
             * and lookahead == 1 (input done one byte at time)
             */
            more--;
         
         /* If the window is almost full and there is insufficient lookahead,
         * move the upper half to the lower one to make room in the upper half.
         */
         } 
         else if (s->strstart >= wsize+MAX_DIST(s)) {
         
            zmemcpy(s->window, s->window+wsize, (unsigned)wsize);
            s->match_start -= wsize;
            s->strstart    -= wsize; /* we now have strstart >= MAX_DIST */
            s->block_start -= (long) wsize;
         
            /* Slide the hash table (could be avoided with 32 bit values
               at the expense of memory usage). We slide even when level == 0
               to keep the hash table consistent if we switch back to level > 0
               later. (Using level 0 permanently is not an optimal usage of
               zlib, so we don't care about this pathological case.)
             */
            n = s->hash_size;
            p = &s->head[n];
            do {
               m = *--p;
               *p = (Pos)(m >= wsize ? m-wsize : NIL);
            } while (--n);
         
            n = wsize;
         #ifndef FASTEST
            p = &s->prev[n];
            do {
               m = *--p;
               *p = (Pos)(m >= wsize ? m-wsize : NIL);
            /* If n is not on any hash chain, prev[n] is garbage but
            * its value will never be used.
            */
            } while (--n);
         #endif
            more += wsize;
         }
         if (s->strm->avail_in == 0) 
            return;
      
        /* If there was no sliding:
         *    strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&
         *    more == window_size - lookahead - strstart
         * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)
         * => more >= window_size - 2*WSIZE + 2
         * In the BIG_MEM or MMAP case (not yet supported),
         *   window_size == input_size + MIN_LOOKAHEAD  &&
         *   strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.
         * Otherwise, window_size == 2*WSIZE so more >= 2.
         * If there was sliding, more >= WSIZE. So in all cases, more >= 2.
         */
        Assert(more >= 2, "more < 2");
      
         n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);
         s->lookahead += n;
      
        /* Initialize the hash value now that we have some input: */
         if (s->lookahead >= MIN_MATCH) {
            s->ins_h = s->window[s->strstart];
            UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
         #if MIN_MATCH != 3
            Call UPDATE_HASH() MIN_MATCH-3 more times
         #endif
         }
        /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,
         * but this is not important since only literal bytes will be emitted.
         */
      
      } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);
   }

/* ===========================================================================
 * Flush the current block, with given end-of-file flag.
 * IN assertion: strstart is set to the end of the current match.
 */
#define FLUSH_BLOCK_ONLY(s, eof) { \
   _tr_flush_block(s, (s->block_start >= 0L ? \
                   (charf *)&s->window[(unsigned)s->block_start] : \
                   (charf *)Z_NULL), \
		(ulg)((long)s->strstart - s->block_start), \
		(eof)); \
   s->block_start = s->strstart; \
   flush_pending(s->strm); \
   Tracev((stderr,"[FLUSH]")); \
}

/* Same but force premature exit if necessary. */
#define FLUSH_BLOCK(s, eof) { \
   FLUSH_BLOCK_ONLY(s, eof); \
   if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \
}

/* ===========================================================================
 * Copy without compression as much as possible from the input stream, return
 * the current block state.
 * This function does not insert new strings in the dictionary since
 * uncompressible data is probably not useful. This function is used
 * only for the level=0 compression option.
 * NOTE: this function should be optimized to avoid extra copying from
 * window to pending_buf.
 */
    local block_state deflate_stored(deflate_state *s, int flush){
    /* Stored blocks are limited to 0xffff bytes, pending_buf is limited
     * to pending_buf_size, and each stored block has a 5 byte header:
     */
      ulg max_block_size = 0xffff;
      ulg max_start;
   
      if (max_block_size > s->pending_buf_size - 5) {
         max_block_size = s->pending_buf_size - 5;
      }
   
    /* Copy as much as possible from input to output: */
      for (;;) {
        /* Fill the window as much as possible: */
         if (s->lookahead <= 1) {
         
            Assert(s->strstart < s->w_size+MAX_DIST(s) ||
         s->block_start >= (long)s->w_size, "slide too late");
         
            fill_window(s);
            if (s->lookahead == 0 && flush == Z_NO_FLUSH) 
               return need_more;
         
            if (s->lookahead == 0) 
               break; /* flush the current block */
         }
      Assert(s->block_start >= 0L, "block gone");
      
         s->strstart += s->lookahead;
         s->lookahead = 0;
      
      /* Emit a stored block if pending_buf will be full: */
         max_start = s->block_start + max_block_size;
         if (s->strstart == 0 || (ulg)s->strstart >= max_start) {
         /* strstart == 0 is possible when wraparound on 16-bit machine */
            s->lookahead = (uInt)(s->strstart - max_start);
            s->strstart = (uInt)max_start;
            FLUSH_BLOCK(s, 0);
         }
      /* Flush if we may have to slide, otherwise block_start may become
         * negative and the data will be gone:
         */
         if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {
            FLUSH_BLOCK(s, 0);
         }
      }
      FLUSH_BLOCK(s, flush == Z_FINISH);
      return flush == Z_FINISH ? finish_done : block_done;
   }

/* ===========================================================================
 * Compress as much as possible from the input stream, return the current
 * block state.
 * This function does not perform lazy evaluation of matches and inserts
 * new strings in the dictionary only for unmatched strings or for short
 * matches. It is used only for the fast compression options.
 */
    local block_state deflate_fast(deflate_state *s, int flush){
      IPos hash_head = NIL; /* head of the hash chain */
      int bflush;           /* set if current block must be flushed */
   
      for (;;) {
        /* Make sure that we always have enough lookahead, except
         * at the end of the input file. We need MAX_MATCH bytes
         * for the next match, plus MIN_MATCH bytes to insert the
         * string following the next match.
         */
         if (s->lookahead < MIN_LOOKAHEAD) {
            fill_window(s);
            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
               return need_more;
            }
            if (s->lookahead == 0) 
               break; /* flush the current block */
         }
      
        /* Insert the string window[strstart .. strstart+2] in the
         * dictionary, and set hash_head to the head of the hash chain:
         */
         if (s->lookahead >= MIN_MATCH) {
            INSERT_STRING(s, s->strstart, hash_head);
         }
      
        /* Find the longest match, discarding those <= prev_length.
         * At this point we have always match_length < MIN_MATCH
         */
         if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {
            /* To simplify the code, we prevent matches with the string
             * of window index 0 (in particular we have to avoid a match
             * of the string with itself at the start of the input file).
             */
            if (s->strategy != Z_HUFFMAN_ONLY) {
               s->match_length = longest_match (s, hash_head);
            }
            /* longest_match() sets match_start */
         }
         if (s->match_length >= MIN_MATCH) {
            check_match(s, s->strstart, s->match_start, s->match_length);
         
            _tr_tally_dist(s, s->strstart - s->match_start,
                           s->match_length - MIN_MATCH, bflush);
         
            s->lookahead -= s->match_length;
         
            /* Insert new strings in the hash table only if the match length
             * is not too large. This saves time but degrades compression.
             */
         #ifndef FASTEST
            if (s->match_length <= s->max_insert_length &&
                s->lookahead >= MIN_MATCH) {
               s->match_length--; /* string at strstart already in hash table */
               do {
                  s->strstart++;
                  INSERT_STRING(s, s->strstart, hash_head);
                    /* strstart never exceeds WSIZE-MAX_MATCH, so there are
                     * always MIN_MATCH bytes ahead.
                     */
               } while (--s->match_length != 0);
               s->strstart++; 
            } 
            else
            #endif
            {
               s->strstart += s->match_length;
               s->match_length = 0;
               s->ins_h = s->window[s->strstart];
               UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);
            #if MIN_MATCH != 3
                Call UPDATE_HASH() MIN_MATCH-3 more times
            #endif
                /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not
                 * matter since it will be recomputed at next deflate call.
                 */
            }
         } 
         else {
            /* No match, output a literal byte */
            Tracevv((stderr,"%c", s->window[s->strstart]));
            _tr_tally_lit (s, s->window[s->strstart], bflush);
            s->lookahead--;
            s->strstart++; 
         }
         if (bflush) FLUSH_BLOCK(s, 0);
      }
      FLUSH_BLOCK(s, flush == Z_FINISH);
      return flush == Z_FINISH ? finish_done : block_done;
   }

/* ===========================================================================
 * Same as above, but achieves better compression. We use a lazy
 * evaluation for matches: a match is finally adopted only if there is
 * no better match at the next window position.
 */
    local block_state deflate_slow(deflate_state *s,int flush){
      IPos hash_head = NIL;    /* head of hash chain */
      int bflush;              /* set if current block must be flushed */
   
    /* Process the input block. */
      for (;;) {
        /* Make sure that we always have enough lookahead, except
         * at the end of the input file. We need MAX_MATCH bytes
         * for the next match, plus MIN_MATCH bytes to insert the
         * string following the next match.
         */
         if (s->lookahead < MIN_LOOKAHEAD) {
            fill_window(s);
            if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {
               return need_more;
            }
            if (s->lookahead == 0) 
               break; /* flush the current block */
         }
      
        /* Insert the string window[strstart .. strstart+2] in the
         * dictionary, and set hash_head to the head of the hash chain:
         */
         if (s->lookahead >= MIN_MATCH) {
            INSERT_STRING(s, s->strstart, hash_head);
         }
      
        /* Find the longest match, discarding those <= prev_length.
         */
         s->prev_length = s->match_length, s->prev_match = s->match_start;
         s->match_length = MIN_MATCH-1;
      
         if (hash_head != NIL && s->prev_length < s->max_lazy_match &&
            s->strstart - hash_head <= MAX_DIST(s)) {
            /* To simplify the code, we prevent matches with the string
             * of window index 0 (in particular we have to avoid a match
             * of the string with itself at the start of the input file).
             */
            if (s->strategy != Z_HUFFMAN_ONLY) {
               s->match_length = longest_match (s, hash_head);
            }
            /* longest_match() sets match_start */
         
            if (s->match_length <= 5 && (s->strategy == Z_FILTERED ||
                 (s->match_length == MIN_MATCH &&
                  s->strstart - s->match_start > TOO_FAR))) {
            
                /* If prev_match is also MIN_MATCH, match_start is garbage
                 * but we will ignore the current match anyway.
                 */
               s->match_length = MIN_MATCH-1;
            }
         }
        /* If there was a match at the previous step and the current
         * match is not better, output the previous match:
         */
         if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {
            uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;
            /* Do not insert strings in hash table beyond this. */
         
            check_match(s, s->strstart-1, s->prev_match, s->prev_length);
         
            _tr_tally_dist(s, s->strstart -1 - s->prev_match,
            s->prev_length - MIN_MATCH, bflush);
         
            /* Insert in hash table all strings up to the end of the match.
             * strstart-1 and strstart are already inserted. If there is not
             * enough lookahead, the last two strings are not inserted in
             * the hash table.
             */
            s->lookahead -= s->prev_length-1;
            s->prev_length -= 2;
            do {
               if (++s->strstart <= max_insert) {
                  INSERT_STRING(s, s->strstart, hash_head);
               }
            } while (--s->prev_length != 0);
            s->match_available = 0;
            s->match_length = MIN_MATCH-1;
            s->strstart++;
         
            if (bflush) FLUSH_BLOCK(s, 0);
         
         } 
         else if (s->match_available) {
            /* If there was no match at the previous position, output a
             * single literal. If there was a match but the current match
             * is longer, truncate the previous match to a single literal.
             */
            Tracevv((stderr,"%c", s->window[s->strstart-1]));
            _tr_tally_lit(s, s->window[s->strstart-1], bflush);
            if (bflush) {
               FLUSH_BLOCK_ONLY(s, 0);
            }
            s->strstart++;
            s->lookahead--;
            if (s->strm->avail_out == 0) 
               return need_more;
         } 
         else {
            /* There is no previous match to compare with, wait for
             * the next step to decide.
             */
            s->match_available = 1;
            s->strstart++;
            s->lookahead--;
         }
      }
    Assert (flush != Z_NO_FLUSH, "no flush?");
      if (s->match_available) {
        Tracevv((stderr,"%c", s->window[s->strstart-1]));
         _tr_tally_lit(s, s->window[s->strstart-1], bflush);
         s->match_available = 0;
      }
      FLUSH_BLOCK(s, flush == Z_FINISH);
      return flush == Z_FINISH ? finish_done : block_done;
   }
